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[thirdparty/openssl.git] / crypto / ec / ec_mult.c
1 /* crypto/ec/ec_mult.c */
2 /*
3 * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
4 */
5 /* ====================================================================
6 * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@openssl.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 * acknowledgment:
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
56 *
57 */
58 /* ====================================================================
59 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
60 * Portions of this software developed by SUN MICROSYSTEMS, INC.,
61 * and contributed to the OpenSSL project.
62 */
63
64
65
66 #include <string.h>
67 #include <openssl/err.h>
68
69 #include "internal/bn_int.h"
70 #include "ec_lcl.h"
71
72
73 /*
74 * This file implements the wNAF-based interleaving multi-exponentation method
75 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>);
76 * for multiplication with precomputation, we use wNAF splitting
77 * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp>).
78 */
79
80
81
82
83 /* structure for precomputed multiples of the generator */
84 typedef struct ec_pre_comp_st {
85 const EC_GROUP *group; /* parent EC_GROUP object */
86 size_t blocksize; /* block size for wNAF splitting */
87 size_t numblocks; /* max. number of blocks for which we have precomputation */
88 size_t w; /* window size */
89 EC_POINT **points; /* array with pre-calculated multiples of generator:
90 * 'num' pointers to EC_POINT objects followed by a NULL */
91 size_t num; /* numblocks * 2^(w-1) */
92 int references;
93 } EC_PRE_COMP;
94
95 /* functions to manage EC_PRE_COMP within the EC_GROUP extra_data framework */
96 static void *ec_pre_comp_dup(void *);
97 static void ec_pre_comp_free(void *);
98 static void ec_pre_comp_clear_free(void *);
99
100 static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group)
101 {
102 EC_PRE_COMP *ret = NULL;
103
104 if (!group)
105 return NULL;
106
107 ret = (EC_PRE_COMP *)OPENSSL_malloc(sizeof(EC_PRE_COMP));
108 if (!ret)
109 {
110 ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
111 return ret;
112 }
113 ret->group = group;
114 ret->blocksize = 8; /* default */
115 ret->numblocks = 0;
116 ret->w = 4; /* default */
117 ret->points = NULL;
118 ret->num = 0;
119 ret->references = 1;
120 return ret;
121 }
122
123 static void *ec_pre_comp_dup(void *src_)
124 {
125 EC_PRE_COMP *src = src_;
126
127 /* no need to actually copy, these objects never change! */
128
129 CRYPTO_add(&src->references, 1, CRYPTO_LOCK_EC_PRE_COMP);
130
131 return src_;
132 }
133
134 static void ec_pre_comp_free(void *pre_)
135 {
136 int i;
137 EC_PRE_COMP *pre = pre_;
138
139 if (!pre)
140 return;
141
142 i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
143 if (i > 0)
144 return;
145
146 if (pre->points)
147 {
148 EC_POINT **p;
149
150 for (p = pre->points; *p != NULL; p++)
151 EC_POINT_free(*p);
152 OPENSSL_free(pre->points);
153 }
154 OPENSSL_free(pre);
155 }
156
157 static void ec_pre_comp_clear_free(void *pre_)
158 {
159 int i;
160 EC_PRE_COMP *pre = pre_;
161
162 if (!pre)
163 return;
164
165 i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
166 if (i > 0)
167 return;
168
169 if (pre->points)
170 {
171 EC_POINT **p;
172
173 for (p = pre->points; *p != NULL; p++)
174 {
175 EC_POINT_clear_free(*p);
176 OPENSSL_cleanse(p, sizeof *p);
177 }
178 OPENSSL_free(pre->points);
179 }
180 OPENSSL_cleanse(pre, sizeof *pre);
181 OPENSSL_free(pre);
182 }
183
184
185 /* TODO: table should be optimised for the wNAF-based implementation,
186 * sometimes smaller windows will give better performance
187 * (thus the boundaries should be increased)
188 */
189 #define EC_window_bits_for_scalar_size(b) \
190 ((size_t) \
191 ((b) >= 2000 ? 6 : \
192 (b) >= 800 ? 5 : \
193 (b) >= 300 ? 4 : \
194 (b) >= 70 ? 3 : \
195 (b) >= 20 ? 2 : \
196 1))
197
198 /*-
199 * Compute
200 * \sum scalars[i]*points[i],
201 * also including
202 * scalar*generator
203 * in the addition if scalar != NULL
204 */
205 int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
206 size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx)
207 {
208 BN_CTX *new_ctx = NULL;
209 const EC_POINT *generator = NULL;
210 EC_POINT *tmp = NULL;
211 size_t totalnum;
212 size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */
213 size_t pre_points_per_block = 0;
214 size_t i, j;
215 int k;
216 int r_is_inverted = 0;
217 int r_is_at_infinity = 1;
218 size_t *wsize = NULL; /* individual window sizes */
219 signed char **wNAF = NULL; /* individual wNAFs */
220 size_t *wNAF_len = NULL;
221 size_t max_len = 0;
222 size_t num_val;
223 EC_POINT **val = NULL; /* precomputation */
224 EC_POINT **v;
225 EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or 'pre_comp->points' */
226 const EC_PRE_COMP *pre_comp = NULL;
227 int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be treated like other scalars,
228 * i.e. precomputation is not available */
229 int ret = 0;
230
231 if (group->meth != r->meth)
232 {
233 ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
234 return 0;
235 }
236
237 if ((scalar == NULL) && (num == 0))
238 {
239 return EC_POINT_set_to_infinity(group, r);
240 }
241
242 for (i = 0; i < num; i++)
243 {
244 if (group->meth != points[i]->meth)
245 {
246 ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
247 return 0;
248 }
249 }
250
251 if (ctx == NULL)
252 {
253 ctx = new_ctx = BN_CTX_new();
254 if (ctx == NULL)
255 goto err;
256 }
257
258 if (scalar != NULL)
259 {
260 generator = EC_GROUP_get0_generator(group);
261 if (generator == NULL)
262 {
263 ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR);
264 goto err;
265 }
266
267 /* look if we can use precomputed multiples of generator */
268
269 pre_comp = EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
270
271 if (pre_comp && pre_comp->numblocks && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == 0))
272 {
273 blocksize = pre_comp->blocksize;
274
275 /* determine maximum number of blocks that wNAF splitting may yield
276 * (NB: maximum wNAF length is bit length plus one) */
277 numblocks = (BN_num_bits(scalar) / blocksize) + 1;
278
279 /* we cannot use more blocks than we have precomputation for */
280 if (numblocks > pre_comp->numblocks)
281 numblocks = pre_comp->numblocks;
282
283 pre_points_per_block = (size_t)1 << (pre_comp->w - 1);
284
285 /* check that pre_comp looks sane */
286 if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block))
287 {
288 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
289 goto err;
290 }
291 }
292 else
293 {
294 /* can't use precomputation */
295 pre_comp = NULL;
296 numblocks = 1;
297 num_scalar = 1; /* treat 'scalar' like 'num'-th element of 'scalars' */
298 }
299 }
300
301 totalnum = num + numblocks;
302
303 wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]);
304 wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]);
305 wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space for pivot */
306 val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
307
308 /* Ensure wNAF is initialised in case we end up going to err */
309 if (wNAF) wNAF[0] = NULL; /* preliminary pivot */
310
311 if (!wsize || !wNAF_len || !wNAF || !val_sub)
312 {
313 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
314 goto err;
315 }
316
317 /* num_val will be the total number of temporarily precomputed points */
318 num_val = 0;
319
320 for (i = 0; i < num + num_scalar; i++)
321 {
322 size_t bits;
323
324 bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar);
325 wsize[i] = EC_window_bits_for_scalar_size(bits);
326 num_val += (size_t)1 << (wsize[i] - 1);
327 wNAF[i + 1] = NULL; /* make sure we always have a pivot */
328 wNAF[i] = bn_compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], &wNAF_len[i]);
329 if (wNAF[i] == NULL)
330 goto err;
331 if (wNAF_len[i] > max_len)
332 max_len = wNAF_len[i];
333 }
334
335 if (numblocks)
336 {
337 /* we go here iff scalar != NULL */
338
339 if (pre_comp == NULL)
340 {
341 if (num_scalar != 1)
342 {
343 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
344 goto err;
345 }
346 /* we have already generated a wNAF for 'scalar' */
347 }
348 else
349 {
350 signed char *tmp_wNAF = NULL;
351 size_t tmp_len = 0;
352
353 if (num_scalar != 0)
354 {
355 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
356 goto err;
357 }
358
359 /* use the window size for which we have precomputation */
360 wsize[num] = pre_comp->w;
361 tmp_wNAF = bn_compute_wNAF(scalar, wsize[num], &tmp_len);
362 if (!tmp_wNAF)
363 goto err;
364
365 if (tmp_len <= max_len)
366 {
367 /* One of the other wNAFs is at least as long
368 * as the wNAF belonging to the generator,
369 * so wNAF splitting will not buy us anything. */
370
371 numblocks = 1;
372 totalnum = num + 1; /* don't use wNAF splitting */
373 wNAF[num] = tmp_wNAF;
374 wNAF[num + 1] = NULL;
375 wNAF_len[num] = tmp_len;
376 if (tmp_len > max_len)
377 max_len = tmp_len;
378 /* pre_comp->points starts with the points that we need here: */
379 val_sub[num] = pre_comp->points;
380 }
381 else
382 {
383 /* don't include tmp_wNAF directly into wNAF array
384 * - use wNAF splitting and include the blocks */
385
386 signed char *pp;
387 EC_POINT **tmp_points;
388
389 if (tmp_len < numblocks * blocksize)
390 {
391 /* possibly we can do with fewer blocks than estimated */
392 numblocks = (tmp_len + blocksize - 1) / blocksize;
393 if (numblocks > pre_comp->numblocks)
394 {
395 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
396 goto err;
397 }
398 totalnum = num + numblocks;
399 }
400
401 /* split wNAF in 'numblocks' parts */
402 pp = tmp_wNAF;
403 tmp_points = pre_comp->points;
404
405 for (i = num; i < totalnum; i++)
406 {
407 if (i < totalnum - 1)
408 {
409 wNAF_len[i] = blocksize;
410 if (tmp_len < blocksize)
411 {
412 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
413 goto err;
414 }
415 tmp_len -= blocksize;
416 }
417 else
418 /* last block gets whatever is left
419 * (this could be more or less than 'blocksize'!) */
420 wNAF_len[i] = tmp_len;
421
422 wNAF[i + 1] = NULL;
423 wNAF[i] = OPENSSL_malloc(wNAF_len[i]);
424 if (wNAF[i] == NULL)
425 {
426 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
427 OPENSSL_free(tmp_wNAF);
428 goto err;
429 }
430 memcpy(wNAF[i], pp, wNAF_len[i]);
431 if (wNAF_len[i] > max_len)
432 max_len = wNAF_len[i];
433
434 if (*tmp_points == NULL)
435 {
436 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
437 OPENSSL_free(tmp_wNAF);
438 goto err;
439 }
440 val_sub[i] = tmp_points;
441 tmp_points += pre_points_per_block;
442 pp += blocksize;
443 }
444 OPENSSL_free(tmp_wNAF);
445 }
446 }
447 }
448
449 /* All points we precompute now go into a single array 'val'.
450 * 'val_sub[i]' is a pointer to the subarray for the i-th point,
451 * or to a subarray of 'pre_comp->points' if we already have precomputation. */
452 val = OPENSSL_malloc((num_val + 1) * sizeof val[0]);
453 if (val == NULL)
454 {
455 ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
456 goto err;
457 }
458 val[num_val] = NULL; /* pivot element */
459
460 /* allocate points for precomputation */
461 v = val;
462 for (i = 0; i < num + num_scalar; i++)
463 {
464 val_sub[i] = v;
465 for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++)
466 {
467 *v = EC_POINT_new(group);
468 if (*v == NULL) goto err;
469 v++;
470 }
471 }
472 if (!(v == val + num_val))
473 {
474 ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
475 goto err;
476 }
477
478 if (!(tmp = EC_POINT_new(group)))
479 goto err;
480
481 /*-
482 * prepare precomputed values:
483 * val_sub[i][0] := points[i]
484 * val_sub[i][1] := 3 * points[i]
485 * val_sub[i][2] := 5 * points[i]
486 * ...
487 */
488 for (i = 0; i < num + num_scalar; i++)
489 {
490 if (i < num)
491 {
492 if (!EC_POINT_copy(val_sub[i][0], points[i])) goto err;
493 }
494 else
495 {
496 if (!EC_POINT_copy(val_sub[i][0], generator)) goto err;
497 }
498
499 if (wsize[i] > 1)
500 {
501 if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) goto err;
502 for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++)
503 {
504 if (!EC_POINT_add(group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) goto err;
505 }
506 }
507 }
508
509 #if 1 /* optional; EC_window_bits_for_scalar_size assumes we do this step */
510 if (!EC_POINTs_make_affine(group, num_val, val, ctx))
511 goto err;
512 #endif
513
514 r_is_at_infinity = 1;
515
516 for (k = max_len - 1; k >= 0; k--)
517 {
518 if (!r_is_at_infinity)
519 {
520 if (!EC_POINT_dbl(group, r, r, ctx)) goto err;
521 }
522
523 for (i = 0; i < totalnum; i++)
524 {
525 if (wNAF_len[i] > (size_t)k)
526 {
527 int digit = wNAF[i][k];
528 int is_neg;
529
530 if (digit)
531 {
532 is_neg = digit < 0;
533
534 if (is_neg)
535 digit = -digit;
536
537 if (is_neg != r_is_inverted)
538 {
539 if (!r_is_at_infinity)
540 {
541 if (!EC_POINT_invert(group, r, ctx)) goto err;
542 }
543 r_is_inverted = !r_is_inverted;
544 }
545
546 /* digit > 0 */
547
548 if (r_is_at_infinity)
549 {
550 if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) goto err;
551 r_is_at_infinity = 0;
552 }
553 else
554 {
555 if (!EC_POINT_add(group, r, r, val_sub[i][digit >> 1], ctx)) goto err;
556 }
557 }
558 }
559 }
560 }
561
562 if (r_is_at_infinity)
563 {
564 if (!EC_POINT_set_to_infinity(group, r)) goto err;
565 }
566 else
567 {
568 if (r_is_inverted)
569 if (!EC_POINT_invert(group, r, ctx)) goto err;
570 }
571
572 ret = 1;
573
574 err:
575 if (new_ctx != NULL)
576 BN_CTX_free(new_ctx);
577 if (tmp != NULL)
578 EC_POINT_free(tmp);
579 if (wsize != NULL)
580 OPENSSL_free(wsize);
581 if (wNAF_len != NULL)
582 OPENSSL_free(wNAF_len);
583 if (wNAF != NULL)
584 {
585 signed char **w;
586
587 for (w = wNAF; *w != NULL; w++)
588 OPENSSL_free(*w);
589
590 OPENSSL_free(wNAF);
591 }
592 if (val != NULL)
593 {
594 for (v = val; *v != NULL; v++)
595 EC_POINT_clear_free(*v);
596
597 OPENSSL_free(val);
598 }
599 if (val_sub != NULL)
600 {
601 OPENSSL_free(val_sub);
602 }
603 return ret;
604 }
605
606
607 /*-
608 * ec_wNAF_precompute_mult()
609 * creates an EC_PRE_COMP object with preprecomputed multiples of the generator
610 * for use with wNAF splitting as implemented in ec_wNAF_mul().
611 *
612 * 'pre_comp->points' is an array of multiples of the generator
613 * of the following form:
614 * points[0] = generator;
615 * points[1] = 3 * generator;
616 * ...
617 * points[2^(w-1)-1] = (2^(w-1)-1) * generator;
618 * points[2^(w-1)] = 2^blocksize * generator;
619 * points[2^(w-1)+1] = 3 * 2^blocksize * generator;
620 * ...
621 * points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator
622 * points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator
623 * ...
624 * points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator
625 * points[2^(w-1)*numblocks] = NULL
626 */
627 int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
628 {
629 const EC_POINT *generator;
630 EC_POINT *tmp_point = NULL, *base = NULL, **var;
631 BN_CTX *new_ctx = NULL;
632 BIGNUM *order;
633 size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num;
634 EC_POINT **points = NULL;
635 EC_PRE_COMP *pre_comp;
636 int ret = 0;
637
638 /* if there is an old EC_PRE_COMP object, throw it away */
639 EC_EX_DATA_free_data(&group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
640
641 if ((pre_comp = ec_pre_comp_new(group)) == NULL)
642 return 0;
643
644 generator = EC_GROUP_get0_generator(group);
645 if (generator == NULL)
646 {
647 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR);
648 goto err;
649 }
650
651 if (ctx == NULL)
652 {
653 ctx = new_ctx = BN_CTX_new();
654 if (ctx == NULL)
655 goto err;
656 }
657
658 BN_CTX_start(ctx);
659 order = BN_CTX_get(ctx);
660 if (order == NULL) goto err;
661
662 if (!EC_GROUP_get_order(group, order, ctx)) goto err;
663 if (BN_is_zero(order))
664 {
665 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER);
666 goto err;
667 }
668
669 bits = BN_num_bits(order);
670 /* The following parameters mean we precompute (approximately)
671 * one point per bit.
672 *
673 * TBD: The combination 8, 4 is perfect for 160 bits; for other
674 * bit lengths, other parameter combinations might provide better
675 * efficiency.
676 */
677 blocksize = 8;
678 w = 4;
679 if (EC_window_bits_for_scalar_size(bits) > w)
680 {
681 /* let's not make the window too small ... */
682 w = EC_window_bits_for_scalar_size(bits);
683 }
684
685 numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks to use for wNAF splitting */
686
687 pre_points_per_block = (size_t)1 << (w - 1);
688 num = pre_points_per_block * numblocks; /* number of points to compute and store */
689
690 points = OPENSSL_malloc(sizeof (EC_POINT*)*(num + 1));
691 if (!points)
692 {
693 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
694 goto err;
695 }
696
697 var = points;
698 var[num] = NULL; /* pivot */
699 for (i = 0; i < num; i++)
700 {
701 if ((var[i] = EC_POINT_new(group)) == NULL)
702 {
703 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
704 goto err;
705 }
706 }
707
708 if (!(tmp_point = EC_POINT_new(group)) || !(base = EC_POINT_new(group)))
709 {
710 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
711 goto err;
712 }
713
714 if (!EC_POINT_copy(base, generator))
715 goto err;
716
717 /* do the precomputation */
718 for (i = 0; i < numblocks; i++)
719 {
720 size_t j;
721
722 if (!EC_POINT_dbl(group, tmp_point, base, ctx))
723 goto err;
724
725 if (!EC_POINT_copy(*var++, base))
726 goto err;
727
728 for (j = 1; j < pre_points_per_block; j++, var++)
729 {
730 /* calculate odd multiples of the current base point */
731 if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx))
732 goto err;
733 }
734
735 if (i < numblocks - 1)
736 {
737 /* get the next base (multiply current one by 2^blocksize) */
738 size_t k;
739
740 if (blocksize <= 2)
741 {
742 ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR);
743 goto err;
744 }
745
746 if (!EC_POINT_dbl(group, base, tmp_point, ctx))
747 goto err;
748 for (k = 2; k < blocksize; k++)
749 {
750 if (!EC_POINT_dbl(group,base,base,ctx))
751 goto err;
752 }
753 }
754 }
755
756 if (!EC_POINTs_make_affine(group, num, points, ctx))
757 goto err;
758
759 pre_comp->group = group;
760 pre_comp->blocksize = blocksize;
761 pre_comp->numblocks = numblocks;
762 pre_comp->w = w;
763 pre_comp->points = points;
764 points = NULL;
765 pre_comp->num = num;
766
767 if (!EC_EX_DATA_set_data(&group->extra_data, pre_comp,
768 ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free))
769 goto err;
770 pre_comp = NULL;
771
772 ret = 1;
773 err:
774 if (ctx != NULL)
775 BN_CTX_end(ctx);
776 if (new_ctx != NULL)
777 BN_CTX_free(new_ctx);
778 if (pre_comp)
779 ec_pre_comp_free(pre_comp);
780 if (points)
781 {
782 EC_POINT **p;
783
784 for (p = points; *p != NULL; p++)
785 EC_POINT_free(*p);
786 OPENSSL_free(points);
787 }
788 if (tmp_point)
789 EC_POINT_free(tmp_point);
790 if (base)
791 EC_POINT_free(base);
792 return ret;
793 }
794
795
796 int ec_wNAF_have_precompute_mult(const EC_GROUP *group)
797 {
798 if (EC_EX_DATA_get_data(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free) != NULL)
799 return 1;
800 else
801 return 0;
802 }
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